Abstract

The calibration of multispectral and hyperspectral imaging systems is typically done in the laboratory using an integrating sphere, which usually produces a signal that is red rich. Using such a source to calibrate environmental monitoring systems presents some difficulties. Not only is much of the calibration data outside the range and spectral quality of data values that are expected to be captured in the field, using these measurements alone may exaggerate the optical flaws found within the system. Left unaccounted for, these flaws will become embedded in to the calibration, and thus, they will be passed on to the field data when the calibration is applied. To address these issues, we used a series of well-characterized spectral filters within our calibration. It provided us with a set us stable spectral standards to test and account for inadequacies in the spectral and radiometric integrity of the optical imager.

The PHILLS 2 derived filter transmissions compared to independent filter transmission measurements for spatial pixel 280: prior to placement of zero order mask (a), after placement of zero order mask (b), and after stray light – frame transfer smear was addressed (c). Note: only three of the six filters employed in the study are displayed.

First order regressions adequately describe the relationship between the sensor’s response and the physical reality for a variety of spectral and lamp intensities throughout the PHILLS 2’s spectral and spatial range.